I use a weighted system myself and feel it is pretty fair and the activity
grades are flexible per project.
40% of the final grade encompasses an average of all studio (project) grades.
Pts are relative per time on project- 2 wks =20 pts, 4wks =40 pts etc. I
have specific rubrics per activity. I usually have 3 projects per 9 weeks.
30% of the final grade is taken from sketchbook assignments (homework).
These are graded once a week -each week worth 10 points
15% of the final grade accounts for their participation in class, discussion,
critiques, clean-up etc. I start everyone with 10 points and "take-off"
points as problems arise.
and the final 15% is taken from averaging the midterm and final test grades.
Not all evaluations are in test form- some are papers or responses to an
issue- but all these type of grades are lumped here in this catagory.

The programe I use in "Making the Grade" by Gradebusters and it works well.
It is a good indication of who the well "disciplined" artists are and who are
not.

All levels of art are graded this way- only the levels of difficulty -or I
will term "responsibility" are higher at the more advanced level.
Hope this helps you...
Kathy in Kalamazoo